Myeloproliferative and lymphoproliferative disorders in Tasmania, 1972-80: patterns in space and time.

During the period 1972-80, 866 patients with myeloproliferative (MP) and lymphoproliferative (LP) disorders were diagnosed in Tasmania. The residential histories of these cases were compared with those of population-based controls. No space-time clustering was demonstrated by individuals of any single diagnosis or group of diagnoses, nor were any regional differences in incidence detected. However, urban-rural differences were observed. Rural exposures were important especially in early childhood and at specific intervals before onset for certain diagnoses. Farm residence in early life yielded heightened relative risks, especially for sufferers from chronic lymphocytic leukemia and acute nonlymphoblastic leukemia. Regional analysis demonstrated elevated risks of residence in orcharding and dairying regions and in an urban-industrial municipality. High risks were associated with latent periods before diagnosis. The findings suggest environmental agents, acting prenatally or in early life, as well as in adult life, as important risk factors in the later development of MP and LP disorders.